In order to measure the position, etc., of a measuring point by a survey apparatus such as a conventional total station (electronic type distance and angle measuring apparatus), it was necessary to collimate a target installed at the measuring point. Recently, in order to relieve labor for collimating a target and decrease errors in collimation due to the peculiarities of an operator, a survey apparatus has been released, which is provided with an automatic collimation device. The automatic collimation device automatically turns a telescope toward the direction of a target by emitting collimation light along the optical axis of the telescope of a survey apparatus, receiving the collimation light reflected by the target, and thus obtaining the direction of the target. The above-described collimation light includes modulation light. The survey apparatus provided with such an automatic collimation device is provided with a remote controller so that a survey can be carried out by a single person from a place apart from the survey apparatus body.
However, if a survey is carried out by using a survey apparatus provided with such an automatic collimation device on the basis of an instruction from the remote controller, since it is necessary to cause the telescope to scan a wide range in order to grasp a target in the visual field of the telescope, automatic collimation takes much time, wherein there is a problem in that the survey is not smoothly carried out.
In order to solve such a problem, a survey apparatus disclosed in Japanese Patent Publication No. 3075348 is known. FIG. 13 and FIG. 14 illustrate the survey apparatus disclosed in Japanese Patent Publication No. 3075348.
As shown in FIG. 13, the survey apparatus 11 is provided with light receiving units 25 and 26 for receiving signal light from a remote controller 27 on its front and back sides. The signal light is concurrently used as guide light by which the position of the remote controller 27 is informed. The respective light receiving units 25 and 26 are shaped like a pyramid as shown in FIG. 14, and are provided with four light receiving planes A, B, C and D.
As an operator who is in the vicinity of a reflection prism 23, such as a corner cube, etc., operates the remote controller 27 toward the survey apparatus, the signal light emitted from the remote controller 27 is made incident into the light receiving unit 25. If the top T of the light receiving unit 25 is turned toward the direction of the remote controller 27, the incident amounts of signal light into the four light receiving planes A, B, C and D become equal to each other. However, when the top T of the light receiving unit 25 is not faced toward the direction of the remote controller 27, the incident amounts of guide light into the four light receiving planes A, B, C and D do not become equal. Therefore, the direction of the remote controller 27 is calculated by comparing outputs from the four light receiving planes A, B, C and D with each other by means of controlling means (not illustrated), and the telescope 12 is turned toward the remote controller 27. As the collimation axis 0 of the telescope 12 is turned to the direction of the remote controller 27, that is, the direction of the reflection prism 23, an LED 31 secured on the front side of the survey apparatus 11 is turned on to inform the operator of this. After that, the telescope 12 can automatically pursue the direction of the reflection prism 23 by an automatic collimation device (not illustrated).
With the survey apparatus, since it is possible to quickly find the direction of the reflection prism 23 by the light receiving units 25 and 26 prior to automatic collimation, it is not necessary to find out the reflection prism 23 by causing a telescope, whose visual field is narrow, to scan a wide range, wherein the time required to finish collimation of the reflection prism 23 can be shortened, and a survey can be smoothly carried out.
However, in the survey apparatus 11 disclosed in Japanese Patent Publication No. 3075384, in order to securely carry out a one-man survey, it is necessary that the survey apparatus 11 can receive signal light (guide light) from a remote controller 27 even if the remote controller 27 and the survey apparatus 11 are not placed in front of each other. Therefore, it is necessary that signal light from the remote controller 27 is irradiated across a wide range, wherein there occurs a problem in that consumption power is increased, and there is another problem in that a range which can be surveyed with a one-man operation is made narrow since the arrival distance of the signal light is shortened if the consumption power is limited.